Various equipment and devices such as snow plows, agricultural tillage implements, earth-moving equipment, clutches, and brakes, as examples, have replaceable parts and surfaces that move relative to other parts or substrates and that may significantly wear during the operational life of such parts. If such parts are not replaced before the wear becomes too severe, extensive collateral damage may occur to adjacent parts and structures. Repairing such collateral damage or replacing damaged parts may be expensive and time-consuming. In addition, a wearing part, such as a carbide-edged snowplow blade, may itself be expensive and require significant time to replace. Therefore, premature prophylactic replacement of such parts represents an unnecessary cost in time and materials.
A sensor for measuring a change of a magnetic field including a magnet for generating a constant magnetic flux and magnetically conductive members for producing a first magnetic field passing through an object capable of influencing the first magnetic field, and a second magnetic field which does not pass through the object, and a magnetic field measuring device located in the second magnetic field for measuring changes in the second magnetic field resulting from changes in the first magnetic field, is described in U.S. Pat. No. 4,229,696 for “Sensor For Measuring Magnetic Field Changes” which issued to Adolf G. Gustafson on Oct. 21, 1980.